In the past few days, those and similarly poignant Twitter posts have appealed to fundamental American values in objecting to the notorious U.C. Davis event, where police pepper-sprayed seated protesters, and to cities generally cracking down on the Occupy movement. The crackdowns have brought a military level of combativeness to what many Americans — even those not in sympathy with the protesters — would normally see as a police, not a military matter.

Police, not military. The distinction may seem academic, even absurd, when police are bringing rifles, helmets, armor, and helicopters to evict unarmed protesters. But it’s an old and critical distinction in American law and ideology and in republican thought as a whole. The 17th-century English liberty writers, on whose ideas much of America’s founding ethos was based, believed that turning the armed might of the state, (necessary in waging war against foreign enemies), to domestic policing of local communities tends to concentrate power in top-down executive action and vitiate treasured things like judiciary process, individual liberty, representative government, and free speech.

Constabulary and judiciary matters, high Whigs came to think, should never be handled by what they condemned as “standing armies.” It’s true, on the other hand, that keeping public order, not just aiding in prosecutions, is a duty of local police. When concerted crowd violence occurs against people and property, policing may be expected to be pretty violent too, and distinctions between combat and policing sometimes naturally blur.